The only way you can do it since you don't want to cut it..Is to let your hair grow naturally (by not relaxing the new growth anymore) till you reach the length you want then cut the remaining relaxed hair. In this process you can trim your relaxed hair slowly by slowly or cut it all at once when you reach the appropriate length .Your hair will not fall out at least mine hasn't fall out till now Just do deep treatments,moisturize your hair and generally take good care of it in this period.You may need to comb your hair lesser since the point the relaxed and the natural hair meets is very fragile.Hope this help.Good luck to you!
All Hair is Good Hair!

It's Not What's ON Your Head, But What's IN Your Head!

Please join/follow my new blog http://vividthoughtsofglory.blogspot.com/